While you all were providing some good information (Thank You very much!), I found the following
info on Napster and 'Scour Exchange' and I thought I would share it:

Napster IP's
IP: 208.178.163.56 mask: 255.255.255.248
IP: 208.178.175.128 mask: 255.255.255.248
IP: 208.49.239.240 mask: 255.255.255.240
IP: 208.49.228.0 mask: 255.255.255.0
IP: 208.184.216.0 mask: 255.255.255.0

Port Direction

5190 Outbound blocks access to AIM servers, users cannot use AIM to chat to others.
4000 Outbound blocks access to ICQ servers, users cannot find other users as easily.
6699 Inbound default port for Napster data connections, however clients can easily change it.
8875 Outbound initial port used by Napster to contact server, useful for logging new Napster
installs.
4444, 5555, 66666, 77777, 88888 Outbound ports used by Napster to connect to servers

The Scour Media Agent uses TCP port 139 for it's SMB transfers.  But if the
machine that is hosting a file on TCP port 80 that one of your users is
accessing you'd pretty much have to shut off web browsing.  Another approach
may be to dissallow web access to scour.net and then your user's can't
access the Scour search engine to even look for stuff.

scour.net is at address 63.145.219.104


Regards,
Donn Shumway
dshumway@hypercom.com
"The best thing about getting older is that you gain sincerity.
Once you learn to fake that, there's nothing you can't do."
-- Tom Smothers